std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>::extract

 

C++

Compiler support

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Named requirements

Feature test macros(C++20)

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Technical specifications

Symbols index

External libraries

 

Containers library

node-handle (C++17)

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

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list

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set

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map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

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span (C++20)

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Member function table

Non-member function table

 

std::flat_multimap

Member types

Member functions

flat_multimap::flat_multimap    flat_multimap::operator= Modifiers flat_multimap::clear flat_multimap::erase flat_multimap::swap flat_multimap::extract flat_multimap::replace flat_multimap::insert flat_multimap::insert_range flat_multimap::emplace flat_multimap::emplace_hint Lookup flat_multimap::count flat_multimap::find flat_multimap::contains flat_multimap::equal_range flat_multimap::lower_bound flat_multimap::upper_bound Iterators flat_multimap::beginflat_multimap::cbegin flat_multimap::endflat_multimap::cend flat_multimap::rbeginflat_multimap::crbegin flat_multimap::rendflat_multimap::crend Capacity flat_multimap::size flat_multimap::max_size flat_multimap::empty Observers flat_multimap::key_comp flat_multimap::keys flat_multimap::value_comp flat_multimap::values

Non-member functions

swap(std::flat_multimap) erase_if(std::flat_multimap)     operator==operator<=>

Helper classes

uses_allocator<std::flat_multimap>

Tags

sorted_equivalent          sorted_equivalent_t

Deduction guides

 

containers extract()&&;		(since C++23)

Extracts adapted containers c. Equivalent to return std::move(c);.

After this operation *this is empty, even if an exception is thrown.

Return value

std::move(c).

Complexity

Constant.

Example

Run this code

#include <cassert>#include <flat_map>#include <print>#include <type_traits>#include <utility>#include <vector>   int main(){std::flat_multimap<int, double> map{{1, 1.1}, {2, 2.2}, {3, 3.3}};constauto size{map.size()};   auto c{std::move(map).extract()};assert(c.keys.size()== size);assert(c.values.size()== size);assert(map.empty());assert(map.keys().empty());assert(map.values().empty());   // The default keys and values containers are std::vector: static_assert(std::is_same_v<decltype(c.keys), std::vector<int>>); static_assert(std::is_same_v<decltype(c.values), std::vector<double>>);   std::println("keys: {}", c.keys);std::println("values: {}", c.values);}

Output:

keys: [1, 2, 3] values: [1.1, 2.2, 3.3]

See also

replace

replaces the underlying containers (public member function)